The present invention is directed to a device for selecting at least two of a plurality of lines and to a device for selecting at least two of a plurality of contact locations arranged in a grid pattern.
In automatic testing units and adapters for printed circuit boards equipped with or without components as well as for wiring matrices in solder or crimp technology, the contacting of the selected measuring locations is usually undertaken via resilient test probes. The resilient test probes arranged according to the grid dimension of the wiring matrix to be tested are secured with spring sleeves that are pressed into a carrier plate and into which the test probes are inserted (Elektronic Produktion und Prueftechnik, November 1979, pages 472 and 473).
European Pat. application No. 0 102 565 discloses a device for the electrical function testing of wiring matrices wherein the ohmic contacting of the measuring locations is replaced by non-touching, ionic contacting via gas discharge paths. To this end, a plurality of gas discharge channels provided with electrodes are located in a carrier plate that can be placed onto the wiring matrices. Gas discharge channels located in a frame of the wiring matrices are open in the direction toward the measuring locations. When, two selected measuring locations are connected to one another in an electrically conductive fashion by an interconnect, then the associated gas discharge channels form two series-connected gas discharge paths that can be ignited by applying an adequately high voltage to the electrodes. A current flow that can be evaluated for testing purposes results with the ignition of the gas discharges. When the ignition of the gas discharges fails to occur or when too low a current flows after an ignition, it can be concluded that an interrupted electrically conductive connection exists between the selected measure locations or that an electrically conductive connection was not formed when the wiring matrix was constructed. When an alternating voltage is superimposed on the voltage applied to the electrodes, then the resulting current change can be measured phase-sensitive relative to the applied alternating voltage and can be utilized for identifying the resistance of a connection existing between the selected measuring locations. The known device thus provides conductivity and insulation measurements, whereby an extremely high reliability is achieved by avoiding ohmic contacts.
In automatic testing units and adapters for printed circuit boards equipped with or without components as well as for wiring matrices in solder or crimp technology, the plurality of measuring locations can amount to as many as a hundred thousand. In a device using resilient test probes as well as using ionic contacting via gas discharge paths, the plurality of required leads and switch elements increases with the plurality of measuring locations. Such an apparatus is very complex and results in high costs.